1. Field
The present disclosure relates generally to vehicles and, in particular, to space vehicles. Still more particularly, the present disclosure relates to a combined pressure and thermal window pane for space vehicles.
2. Background
Some spacecraft may be designed to repeatedly be launched into space and re-enter the atmosphere. These types of spacecraft may be subjected to temperatures that may reach over about 1,500 degrees Celsius when re-entering the atmosphere. Further, loads also may be placed on different structures of the spacecraft during re-entry as well as during launching of the vehicle into space.
These types of events may result in undesired inconsistencies in window systems in a spacecraft. For example, without limitation, a window may not provide the optical clarity that may be desired for observing objects outside of the spacecraft or the desired strength for a subsequent re-entry.
Window systems for space vehicles that re-enter the atmosphere may have window systems designed to withstand those types of environments. A window system in a space vehicle that re-enters the atmosphere may use multiple panes. Window systems may typically have two types of window panes.
One type of window pane may be used for pressure protection, while another type of window pane may be used for thermal protection. The pressure may be internal pressure inside the spacecraft. The thermal protection may be protection against heat from the exterior of the spacecraft. These designs may be more complex and may weigh more than desired. Further, when two types of window panes are used in a window system, the number of components used in the spacecraft may be increased in a manner that results in more maintenance than desired.
Some currently used window panes may be comprised of fused silica. Fused silica may have optical qualities that make fused silica desirable for use in window panes. However, the brittleness of this type of material may result in more and/or thicker window panes being used in a window system than is desirable.
For example, without limitation, the optical clarity provided by a window pane comprised of fused silica may decrease as the thickness of the window pane increases. Consequently, additional window panes may be used in addition to and/or instead of increasing the thickness of the window pane when the window pane does not perform as desired.
Further, window panes comprised of fused silica may not provide a desired level of thermal protection. For example, without limitation, window panes comprised of fused silica may be unable to provide a desired level of protection from heat encountered during re-entry of a space vehicle from outer space into the atmosphere and/or provide a desired level of protection from the cold environment encountered in outer space.
Therefore, it would be desirable to have a method and apparatus that takes into account at least some of the issues discussed above, as well as possibly other issues.